Mammals Study Materials

Mammals Study Materials and therian mammals (marsupials and placentals) and all descendants of that ancestor.[6] Since this ancestor lived in the Jurassic period, Rowe's Mammals are the vertebrates within definition excludes all animals from the the class Mammalia a clade of endothermic amniot earlier Triassic, despite the fact that Triassic fossils es distinguished from reptiles (including birds) by in the Haramiyida have been referred to the the possession of a neocortex (a region of the Mammalia since the mid-19th century. brain), hair, three middle ear bones, and mammary glands. Females of all mammal species nurse their Class Mammalia young with milk, secreted from the mammary glands.  Subclass Prototheria: monotremes: echidnas and the platypus Classification  Subclass Theriiformes: live-bearing mammals and their prehistoric relatives Mammal classification has been through several  Infraclass † Allotheria: multituberculates iterations since Carl Linnaeus initially defined the  Infraclass † Eutriconodonta: eutriconodonts class. No classification system is universally  Infraclass Holotheria: modern live-bearing accepted; McKenna & Bell (1997) and Wilson & mammals and their prehistoric relatives Reader (2005) provide useful recent  Superlegion †Kuehneotheria compendiums. George Gaylord Simpson's  Supercohort Theria: live-bearing mammals "Principles of Classification and a Classification of  Cohort Marsupialia: marsupials Mammals" (AMNH Bulletin v. 85, 1945)  Magnorder Australidelphia: Australian provides systematics of mammal origins and marsupials and the monito del monte relationships that were universally taught until the  Magnorder Ameridelphia: New World end of the 20th century. Since Simpson's marsupials. Now considered paraphyletic, classification, the paleontological record has been with shrew opossums being closer to recalibrated, and the intervening years have seen australidelphians.[13] much debate and progress concerning the  Cohort Placentalia: placentals theoretical underpinnings of systematization itself,  Magnorder Xenarthra: xenarthrans partly through the new concept of cladistics.  Magnorder Epitheria: epitheres Though field work gradually made Simpson's  Superorder †Leptictida classification outdated, it remains the closest thing  Superorder Preptotheria to an official classification of mammals.  Grandorder Anagalida: lagomorphs, rodents and elephant shrews Definitions  Grandorder Ferae: carnivorans, pangolins, †creodonts and relatives The word "mammal" is modern, from the scientific  Grandorder Lipotyphla: insectivorans name Mammalia coined by Carl Linnaeus in 1758,  Grandorder Archonta: bats, primates, colugo derived from the Latin mamma ("teat, pap"). In an s and treeshrews influential 1988 paper, Timothy Rowe defined  Grandorder Ungulata: ungulates Mammalia phylogenetically as the crown group of  Order Tubulidentata incertae sedis: aardvark mammals, the clade consisting of the most recent  Mirorder Eparctocyona: common ancestor of †condylarths, whales and artiodactyls (even- living monotremes(echidnas and platypuses) toed ungulates) 1 Download Study Materials on www.examsdaily.in Follow us on FB for exam Updates: ExamsDaily Mammals Study Materials

 Mirorder †Meridiungulata: South American horns have a single cervix that connects to the ungulates vagina, a bicornuate, which consists where two  Mirorder Altungulata: perissodactyls (odd- uterine horns that are connected distally but toed separate medially creating a Y-shape, and a ungulates), elephants, manatees and hyraxes. simplex, which has a single uterus.

Reproductive system Humans and other mammals

The ancestral condition for mammal reproduction is In human culture the birthing of relatively undeveloped, either through direct vivipary or a short period as soft- Non-human mammals play a wide variety of roles shelled eggs. This is likely due to the fact that the in human culture. They are the most popular of pets, torso could not expand due to the presence with tens of millions of dogs, cats and other animals of epipubic bones. The oldest demonstration of this including rabbits and mice kept by families around reproductive style is with Kayentatherium, which the world. Mammals such as mammoths, horses and produced undeveloped perinates, but at much higher deer are among the earliest subjects of art, being litter sizes than any modern mammal, 38 found in Upper Paleolithic cave paintings such as specimens.[108] In placental mammals, a radical at Lascaux. Major artists such as Albrecht change happened, the conversion of the epipubic Dürer, George Stubbs and Edwin Landseer are into genital bacculum bones or complete loss; this known for their portraits of mammals. Many species allowed the torso to be able to expand and thus of mammals have been hunted for sport and for produce developed offspring. food; deer and wild boar are especially popular as game animals. Mammals such In male placentals, the penis is used both for as horses and dogs are widely raced for sport, often urination and copulation. Depending on the species, combined with betting on the outcome. There is a an erection may be fueled by blood flow into tension between the role of animals as companions vascular, spongy tissue or by muscular action. A to humans, and their existence as individuals penis may be contained in a sheath when not erect, with rights of their own. Mammals further play a and some placentals also have a penis bone wide variety of roles in literature, film, mythology, (baculum). Marsupials typically have forked penises and religion. while the monotreme penis generally has four heads with only two functioning. The testes of most Hybrids mammals descend into the scrotum which is typically posterior to the penis but is often anterior Hybrids are offspring resulting from the breeding of in marsupials. Female mammals generally have two genetically distinct individuals, which usually a clitoris, labia majora and labia minora on the will result in a high degree of heterozygosity, outside, while the internal system contains though hybrid and heterozygous are not paired oviducts, 1-2 uteri, 1-2 cervices and a vagina. synonymous. The deliberate or accidental Marsupials have two lateral vaginas and a medial hybridizing of two or more species of closely vagina. The "vagina" of monotremes is better related animals through captive breeding is a human understood as a "urogenital sinus". The uterine activity which has been in existence for millennia systems of placental mammals can vary between a and has grown for economic purposes. Hybrids duplex, were there are two uteri and cervices which between different subspecies within a species (such open into the vagina, a bipartite, were two uterine as between the Bengal tiger and Siberian tiger) are 2 Download Study Materials on www.examsdaily.in Follow us on FB for exam Updates: ExamsDaily Mammals Study Materials

known as intra-specific hybrids. Hybrids between the same or adjacent areas will interbreed with each different species within the same genus (such as other. Some hybrids have been recognized as between lions and tigers) are known as interspecific species, such as the red wolf (though this is hybrids or crosses. Hybrids between different controversial) genera (such as between sheep and goats) are known as intergeneric hybrids. Natural hybrids will occur in hybrid zones, where two populations of species within the same genera or species living in

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